It is often necessary to separate synthetic and naturally occurring nucleic acid materials such as DNA, RNA, oligonucleotides, and the like from various biological samples and other fluids such as cell lysates, synthetic reaction mixtures, PCR reaction mixtures, and the like. Such separations can be very important steps in various analytical procedures, synthetic procedures, and research activities. Any such method should be reliable, efficient, easy to implement, and not destructive of the nucleic acid materials.
In many instances, positively charged polymers such as polylysine and polyethyleneimine based materials have been used in gene delivery and various nucleic acid purification processes, since these types of molecules can effectively capture and retain negatively charged nucleic acid materials. In such processes, the charged polymers are typically immobilized on a solid surface, such as a magnetic particle, polystyrene particles or the like. The charged polymer is then contacted with a sample containing a nucleic acid material typically at a pH of less than 8. This causes the nucleic acid material to bind to the positively charged polymer. Impurities such as proteins and carbohydrates do not bind and can be washed away from the sample. The bound nucleic acid material is then released from the polymer under high pH conditions so as to achieve purification. However, in many instances the nucleic acid materials bind very strongly to the polymer thereby requiring use of high pH and high temperature conditions to release the bound nucleic acid from the polymer. However, the nucleic acid materials can be permanently denatured by such high temperature and alkaline reaction conditions. Therefore, there is a need for methods and materials which allow for the separation and purification of nucleic acid materials under relatively mild pH and temperature conditions. As will be explained in detail hereinbelow, the present invention allows for the binding, separation, and release of nucleic acid materials at room temperature and under mildly alkaline conditions. These and other advantages of the invention will be apparent from the discussion and description which follow.